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NAME

       ctime, ctime_r - convert a time value to a date and time string

SYNOPSIS

       #include <time.h>

       char *ctime(const time_t *clock);

       char *ctime_r(const time_t *clock, char *buf);

DESCRIPTION

       For  ctime():    The  functionality described on this reference page is
       aligned with the ISO C standard. Any conflict between the  requirements
       described  here and the ISO C standard is unintentional. This volume of
       IEEE Std 1003.1-2001 defers to the ISO C standard.

       The ctime() function shall  convert  the  time  pointed  to  by  clock,
       representing time in seconds since the Epoch, to local time in the form
       of a string. It shall be equivalent to:

              asctime(localtime(clock))

       The asctime(),  ctime(),  gmtime(),  and  localtime()  functions  shall
       return  values  in  one  of  two  static  objects:  a  broken-down time
       structure and an array of char. Execution of any of the  functions  may
       overwrite the information returned in either of these objects by any of
       the other functions.

       The ctime() function need not be reentrant.  A  function  that  is  not
       required to be reentrant is not required to be thread-safe.

       The  ctime_r()  function  shall convert the calendar time pointed to by
       clock to local time in exactly the same form as  ctime()  and  put  the
       string  into  the  array  pointed to by buf (which shall be at least 26
       bytes in size) and return buf.

       Unlike ctime(), the thread-safe version ctime_r() is  not  required  to
       set tzname.

RETURN VALUE

       The  ctime()  function  shall  return the pointer returned by asctime()
       with that broken-down time as an argument.

       Upon successful completion, ctime_r() shall return  a  pointer  to  the
       string  pointed to by buf. When an error is encountered, a null pointer
       shall be returned.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Values for the broken-down time structure can be  obtained  by  calling
       gmtime()   or   localtime().  The  ctime()  function  is  included  for
       compatibility  with  older  implementations,  and  does   not   support
       localized   date   and  time  formats.   Applications  should  use  the
       strftime() function to achieve maximum portability.

       The ctime_r() function is thread-safe and  shall  return  values  in  a
       user-supplied  buffer instead of possibly using a static data area that
       may be overwritten by each call.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       asctime() , clock() , difftime() , gmtime() , localtime() , mktime()  ,
       strftime()  ,  strptime()  ,  time()  ,  utime() , the Base Definitions
       volume of IEEE Std 1003.1-2001, <time.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .